Back-of-the-envelope
- Road area. World road length ≈ 60–70 million km. Using an average paved width of ~8–10 m ⇒ area ≈ (0.9–1.3)×10¹² m². Earth’s surface is 5.1×10¹⁴ m², so roads cover ~0.09–0.13% of the planet.
- Albedo change. Dark asphalt is ~0.05–0.10. “White” coatings can push toward ~0.4–0.6 (fresh), but weathering quickly dulls them. So a plausible Δalbedo for roads is +0.2 to +0.5.
- Global albedo change. Δα_global ≈ (road fraction) × (Δalbedo_road) ≈ (0.001)×(0.2–0.5) ≈ +0.0002 to +0.0005.
- Radiative forcing. Globally averaged incoming sunlight ≈ S₀/4 ≈ 340 W m⁻². Forcing from an albedo change is ΔF ≈ −Δα_global × 340 ≈ −0.07 to −0.17 W m⁻².
- Temperature response. Using a standard sensitivity ~0.8 °C per W m⁻² (≈3 °C per CO₂ doubling): ΔT ≈ −0.05 to −0.14 °C at equilibrium.
White roads could potentially be blinding, but yeah something lighter than what we do currently could be very worthwhile. It'd have much higher nighttime visibility too.
I was thinking you could potentially engineer them to reflect IR light, but I feel like dust and dirt would probably quickly eat into the effectiveness. The question is whether it'd really make a difference on a global scale at all.
Back-of-the-envelope - Road area. World road length ≈ 60–70 million km. Using an average paved width of ~8–10 m ⇒ area ≈ (0.9–1.3)×10¹² m². Earth’s surface is 5.1×10¹⁴ m², so roads cover ~0.09–0.13% of the planet.
- Albedo change. Dark asphalt is ~0.05–0.10. “White” coatings can push toward ~0.4–0.6 (fresh), but weathering quickly dulls them. So a plausible Δalbedo for roads is +0.2 to +0.5.
- Global albedo change. Δα_global ≈ (road fraction) × (Δalbedo_road) ≈ (0.001)×(0.2–0.5) ≈ +0.0002 to +0.0005.
- Radiative forcing. Globally averaged incoming sunlight ≈ S₀/4 ≈ 340 W m⁻². Forcing from an albedo change is ΔF ≈ −Δα_global × 340 ≈ −0.07 to −0.17 W m⁻².
- Temperature response. Using a standard sensitivity ~0.8 °C per W m⁻² (≈3 °C per CO₂ doubling): ΔT ≈ −0.05 to −0.14 °C at equilibrium.
White roads could potentially be blinding, but yeah something lighter than what we do currently could be very worthwhile. It'd have much higher nighttime visibility too.
I'm thinking about light colored roads that seem to be made of concrete. See them here and there. Seemed to be more of them when I was a kid.
Wonder if that would make a substantial difference? Much brighter than asphalt but not bright enough to bother drivers.
I was thinking you could potentially engineer them to reflect IR light, but I feel like dust and dirt would probably quickly eat into the effectiveness. The question is whether it'd really make a difference on a global scale at all.
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> White roads could potentially be blinding
Hell I was just walking down the street a minute ago and thinking the same! It's October ffs! (It IS October right?)
Teslas will start crashing like there’s no tomorrow.
So nothing much will change?